Overheating on the Highway...

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mjtoll23

almost a TT-R
Apr 14, 2007
96
0
0
VA
I am having some overheating issues with my supra. Its a 1jz 5 speed. The car runs and drives great, but is getting hot on the highway or any consistent speed (45mph+). If I pull over or come to a stop light, it slowly cools down.

I have a koyo radiator with dual flex a lite fans. I have a 180 and 200 degree relay set up for them. The 180 comes on, I havent seen the 200 degree fan come on? Could be a sensor issue, but with a consistent speed, I figured the fans shouldnt be an issue. I just replaced the thermostat and the radiator cap.

Is there a bleed valve for the coolant system? It seems to be bled, but Im at a loss for ideas here. Anyway to test the stock gauge? Any ideas or suggestions would be appreciated.

Thanks,
Mike
 
D

di_rosa

never ending project ...
Apr 2, 2005
215
0
0
toronto
your fans have the polarity reversed? they are pulling instead of pushing. i did that before, and whenever i would drive fast, the fans would push against the air coming in, and not cool the rad. picture the airflow like this:

--> <--

so it would cancel each other out, and not cool........just a thought since i'm dumb enough to do it, figured other people could too.
 
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mjtoll23

almost a TT-R
Apr 14, 2007
96
0
0
VA
IJ.;1382696 said:
Do you have the factory undertrays in place?
Click to expand...

I do not have the factory undertrays.

The fans blow the correct direction.

I never had this problem before, it just started about a month ago. Nothing new or modified...
 
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mjtoll23

almost a TT-R
Apr 14, 2007
96
0
0
VA
Thanks for the responses. I do need to get an undertray, its on my list of things to buy.

Im going to pull the radiator and see if it may be clogged up either inside or out.
 
Deeznuts

Deeznuts

New Member
Apr 24, 2005
80
0
0
VA
I had the same prob. I got high output fans relocated the batt to the rear and no more over heating. I got two fans your really only need one 4000cfm fan the one that in automatic controlled I mounted infront of the turbos on the radiator so it moves air onto those.
 
NTRA08

NTRA08

TWINKY
Jun 10, 2008
530
0
0
36
Conroe, Texas
For a while my car would overheat like yours. JDUB suggested that I cut off the jiggle valve on the thermostat and it might fix it. I did so and I haven't oveheated since. I used to run electric fans. I still think that stock clutch fan is the best.
 
swaq

swaq

posts++;
May 24, 2005
1,351
0
36
Oregon -> Arizona
www.SwaqValley.com
Poodles;1383868 said:
Yes it is. When my fan clutch took a shit on me, it would be fine on the highway as it was literally just freewheeling.
Click to expand...

This isn't consistent with what I've been seeing, but there could be something else wrong with my cooling system (though I think I've replaced every component in it by now). Do you have a dedicated temperature gauge or are you just going by the stock one?
 
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mjtoll23

almost a TT-R
Apr 14, 2007
96
0
0
VA
Well I believe I have solved my problem. I am running dual fans and dual relays. The fan on the passenger side was not turning on due to a faulty temp sender (200 degree). I tested this out with a laser thermometer. It was reading 215 on the sensor and the fan wasnt kicking on. The driver side fan (160 sensor) was cooling enough in traffic and at idle, but not enough for the highway. The passenger side fan has the a/c fan in front of it along with the evaporator and a large front mount intercooler. I jumped the sensor on the fan and drove around for an hour in 95 degree heat and it did not get hot.

On a side note, I think its time for the starter relay mod. The circuit has been acting up on me lately and it had enough by the end of today. It wouldnt start in my driveway, came back an hour later and cranked right up!

Good times.... Anyways, thanks for all the help and suggestions guys.
 
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HommerSimpson

New Member
Dec 31, 2007
1,067
0
0
New Smyrna Beach Florida
you must have insufencent (sp) cooling system... my ele fan never comes on at highway speed with a/c on and you can not put any bigger intercooler in car then i got..so something is amist.. you should not need a fan pulling air in threw the front of the car going down the highway at speed...



edit.. sorry i ment when a/c off as its always on when a/c is
 
M

mjtoll23

almost a TT-R
Apr 14, 2007
96
0
0
VA
HommerSimpson;1384090 said:
you must have insufencent (sp) cooling system... my ele fan never comes on at highway speed with a/c on and you can not put any bigger intercooler in car then i got..so something is amist.. you should not need a fan pulling air in threw the front of the car going down the highway at speed...



edit.. sorry i ment when a/c off as its always on when a/c is
Click to expand...

In theory, I would agree. All I can say, is that I ran both fans and it stopped getting hot. It never overheated per say, just got up to about 3/4 on the factory gauge.

Do you have an undertray? Like others have said, Im sure that would be the difference for the highway cooling...
 
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HommerSimpson

New Member
Dec 31, 2007
1,067
0
0
New Smyrna Beach Florida
nope no undertray.. i will be making one... but it will be huge ....

i have a 4 inch intercooler that is prob as big as anyting put in a supra..but i also have a aluminum rad that i got from summit to fit a circle track car.. and then im using a dodge something or other fan shourd that totaly covers the radiator with 1 fan with 2 speeds...
 
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